The invention relates to multichannel magnetic transducers having improved wear characteristics and to the method of manufacturing such transducers. The invention is particularly useful for applications where the transducer is in direct contact with the recording medium, such as longitudinal tape drives utilized in analog or digital, instrumentation or audio tape recorders.
Transducers in direct contact with the recording medium generally exhibit extensive wear in the transducer-to-medium interface area due to abrasion effected by the medium. As is well known, such wear is undesirable, since it results in limited head life. Consequently, replacement heads have to be provided frequently at considerable cost.
An effort has been made heretofore to extend transducer life, such as by utilization of various wear-resistant materials in the transducer structure. For example, there are known prior art transducers having magnetic pole tips mounted in a tip plate made of extremely hard, wear-resistant nonmagnetic alloys. However, machining of such extremely hard materials is very difficult; and, thus, their use for tip plates is impractical. Other known prior art transducers utilize tip plates having hard, nonmagnetic, wear-resistant alloys deposited by a known method on a pre-machined relatively soft nonmagnetic metal to avoid the problem of machining hard alloys. The latter method is expensive, since it includes complicated, time consuming method steps, as well as steps requiring great precision of fabrication.
U.S. Pat. Nos. 3,843,964 and 3,909,932, both commonly assigned to Ampex Corporation, represent another group of prior art multichannel transducers and manufacturing methods where magnetic pole tips are supported by a wear-resistant, nonmagnetic ceramic holder. This type of transducer does not provide necessary electromagnetic shielding protection from surrounding radiation fields. Therefore, these multichannel transducer structures are not suitable for applications where external noise picked up by the transducer would seriously distort the output signal therefrom. For example, in wideband instrumentation recording such noise might cause intolerable degradation of the high frequency signals.